Corythion aerophila Decloitre, 1950 *)
Basionym: Corythion dubium var. aerophila Decloitre, 1950

Diagnosis: Shell with a large visor preceding the pseudostome, much larger than in C. dubium and featuring several rows of scales. Finally, this visor, forming a peristomial region, appears to be added to the theca and is connected to it by a strong constriction. The posterior edge of the pseudostome is straight or even convex. The pseudostome is bordered by very fine small beads that are difficult to see except under phase contrast. The plates of the shell are very small, arranged without order, except for those bordering the shell laterally. When a shell breaks, the visor detaches as a block from the rest of the shell. The ventral part is almost flat, while the dorsal part is regularly rounded.

Dimensions: According to Decloitre (1950, 1956, 1965): Shell length 30—60 µm; width 20—35 µm. Siemensma (2026, Arcella.nl): Length 64 µm; width 40 µm (=1).

Ecology: Soil.

Distribution: France, Belgium, England, Norway, Greenland, Iceland (Decloitre, 1965); Sweden (Siemensma, 2026, Arcella.nl).

*) Taxonomic note: Corythion dubium var. aerophila Decloitre, 1950 is changed to Corythion aerophila Decloitre, 1950.
Because the name was published before 1961 using the abbreviation var., it is deemed subspecific under Article 45.6.4, unless explicitly proposed as infrasubspecific. As a species-group name, it is simultaneously established at both species and subspecies rank under the Principle of Coordination (Art. 46.1), with identical authorship, date, and type. Accordingly, when treated at species rank, the valid name is Corythion aerophila Decloitre, 1950.